A conventional ventilation device for a power stapler is shown in FIG. 1 and comprises a protrusion 10 extending from a rear end of a power stapler and the protrusion 10 has a notch 11 defined therethrough. The notch 11 communicates with the interior of the power stapler so that pressure air will eject from the notch 11 when shooting a staple. A circular flange 14 extends from the rear end of the power stapler and encloses the protrusion 10. A cap 13 has a passage 12 defined radially therein and a groove 15 defined in the inner periphery thereof so that the cap 13 is mounted to the rear end of the power stapler with the circular flange 14 engaged with the groove 15. Because there is no reliable positioning means to let the cap 13 secure to the circular flange 14 so that the connection of the cap 13 and the circular flange 14 could be loosened by the pressure air flow. Furthermore, the direction of the air ejected could result the wood powder raises so that the users will like to adjust the direction of the air flow so as not to blow the wood powder around the users.
The present invention intends to provide a ventilation device of a power stapler wherein the protrusion on the rear end of the power stapler has a boss extending therefrom and the cap has a plurality of dents so that the cap is positioned by receiving the boss in one of the dents when rotating an angle. Therefore, the direction of the ejection of the air flow can be adjusted.